How to Use the Marathon Hill Pace Calculator
Running at the same effort naturally slows you down on an uphill and speeds you up on a downhill. If you run hilly sections targeting your flat-ground pace, you risk burning out on the climbs or overspeeding into injury on the descents. Enter your flat-ground goal pace and the grade of your uphill and downhill sections to calculate the realistic pace you should hold on each part.
As a general rule, uphill pace slows by about 5 seconds per mile for every 1% of grade, since extra energy is needed to work against gravity. Pacing by heart rate or perceived effort rather than pure speed is usually more accurate on climbs.
On downhills, gentle grades (8% or less) let gravity naturally speed you up, but grades steeper than that increase landing impact and braking demands, which reduces your speed gains and actually raises injury risk. Use the calculated pace as a baseline, then adjust flexibly based on how you feel and the surface conditions on race day.
Frequently Asked Questions
As a general rule, expect your pace to slow by about 5 seconds per mile for every 1% of grade. To keep your heart rate similar to flat ground, it's better to pace uphills by effort rather than speed.
On gentle downhills (8% grade or less), gravity naturally speeds you up. But on steeper grades, landing impact and braking forces increase, raising injury risk while actually reducing your speed gains.
Hill repeats on grades similar to your race course build both the strength needed for uphills and the landing control needed for downhills. Training only on flat ground can leave you fatigued faster than expected on race-day hills.